In order to control operation of a microactuator of a manipulator or the like used in a micromachine or gene manipulation, it is requested that the microactuator is small-sized and light-weighed for detecting and measuring a displacement amount of a moving object by a resolution of from micrometer to nanometer. Conventionally, in detecting and measuring a displacement amount by the resolution of from micrometer to nanometer, various systems have been proposed and reduced into practice. Representatively, there can be pointed out laser measurement by a method of irradiating an object with laser light and detecting a phase difference brought about in accordance with displacement of the object, a method of using a phenomenon of interference between the laser light and reference light or the like.
A displacement amount in a nanometer order can be measured by using laser measurement technology or the like. However, whereas a size of a microactuator is in an order of from several centimeters to ten and several centimeters, in the laser measurement, a light source, a measuring portion for detecting and measuring a phase difference or interference and the like become considerably large-sized. Further, the apparatus becomes expensive since a complicated optical system and a measuring frequency at a high frequency are used and the like in order to promote the resolution.